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Flush goes the toilet. The water swirls around the tank and then exits in a big whoosh. But which way does the water swirl around, clockwise or counterclockwise? Many people think the direction the water rotates is caused by the Coriolis Effect, which is also the name of our newest Gizmo.

The basic idea of the Coriolis effect is that when an object is launched, you have to consider the motion of the platform it was launched from and the speed and direction it was propelled. The Gizmo illustrates this with two characters, Willie and June, playing catch. First, as they play catch while riding on trains, students will see that the motion of Willie’s train causes his throw to be deflected to the right. Next, Willie and June ride on a merry-go-round, where rotational motion causes Willie’s throw to go awry. This applies directly to the Earth, where Earth’s rotational motion causes Willie’s throws to be deflected.

Next, students can go through several real-world examples of the Coriolis effect, including global wind patterns, air circulation around weather systems, and the formation of circulating storms such as hurricanes. But no, toilet bowls are not on the list. While the Coriolis effect is powerful enough to form massive storms, it is too weak to influence the water in your toilet.